A two stage turbocharger system typically includes a small high-pressure turbocharger and a larger low-pressure turbocharger. A two stage turbocharger system may be used with an internal combustion engine of a vehicle in order to improve engine performance, for example, by providing higher torque at low speeds or to reduce turbo lag.
A two stage turbocharger system of an internal combustion engine is typically driven by the exhaust gases. Various layouts of two stage turbocharger systems as well as various methods of operating the two stage turbocharger systems are known, for example from U.S. Pat. No. 4,930,315 and U.S. Pat. No. 6,981,375.
To lower exhaust emissions, particularly of vehicles, in order to meet ever more stringent environmental standards, a particle filter and/or oxidation catalyst may be provided which are in flow communication with the exhaust gases generated by the engine. It is known to provide an oxidation catalyst close to the engine and an underfloor particle filter. However, a vehicle equipped with such an engine has an undesirably low performance and loss of heat when the particle filter is regenerated.
It is an object of the invention to provide an arrangement of a two stage turbocharger for an internal combustion engine so as to increase the performance and lower the emissions of the engine.